Jidan,
On Dec 29, 2009, at 6:16 AM, z丹丹 wrote:
> Your asumption is right. Here is the analysis I wan t to do. I have a 3D
> fiducial surface , based on this fiducial surface ,let's say, "template", I
> generated some simulated fiducial surface with some deformation, let's say
> "subject". So here I know the "deformation vectors" for each vertex between
> the template and the subject in the original 3D fiducial surface "space".
> Then I use Caret to do spherical registration from those subjects to the
> template.
> I want to check how these " deformation vectors " I got from Caret are
> different from my generated "deformation vectors". But the problem for me is,
> after Caret registration, the " deformation vectors" is based on the
> spherical space. While my generated "deformation vectors" are in the 3d
> fiducial surface space, it's not comparible for these two vectors. That's why
> I want to know whether I can put the deformed subject sphere back into the
> fiducial surface representation. In that way, I can calculate the diffe r
> ence in the fiducial space. While from your comments it seems that the
> answer is no, could you give me some suggestions about how to calculate the
> difference of the deformation vectors which are not in the same space?
> Generating the deformation vectors in the spherical space is the last thing I
> want to do because you never know how it likes in the real fiducial surface
> representation.
Given these objectives, it should be possible to do what you want.
Let's call your starting template fiducial 'TF.coord' Your deformed template
fiducial surface, DTF.coord, also has the same number of nodes, I gather -
allowing you to create and display a node-based deformation vector.
When you register DTF.coord to TF.coord, you will get a new surface that will
be named 'Resampled_DTF.coord' if you select 'Resampled_' as the prefix on the
Deformation tab when you run spherical deformation. If you create a
deformation field between 'Resampled_DTF.coord' and 'TF.coord', it should
reflect the node correspondences resulting from the registration process.
Bear in mind that the deformation is unlikely to perform well unless the
landmarks you choose are close to and effectively surround whatever local
deformations were used to generate DTF.coord. Thus, if you created, say, a
restricted deformation of one region (e.g., smoothing of the frontal pole), you
would not obtain good registration using only the standard 'core 6' landmarks.
Let me know if this is unclear.
>
David
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